In vitro digestion simulation of medium chain fatty acids using static and dynamic protocols

Abstract

Food biophysics research has more recently focused on understanding the behavior of foods within the human gastrointestinal (GI) tract. In vitro models allow the screening of foods and are helpful for better understanding digestive kinetics. They can be used to evaluate the metabolic properties of macronutrients such as medium-chain fatty acids (MCFAs). In this work, a dynamic GI model system [Pinheiro et al., Food Hydrocolloids, 52, (2016) p. 460467] and the static in vitro digestion protocol [Brodkorb et al., Nature Protocols, 14, (2019) p. 9911014] have been applied to investigate the gastric digestion of medium-chain triglyceride (MCT) oil samples. The total release of free fatty acids (FFA) was measured using a pH-stat device and gas chromatography (GC) was used to obtain FFA profiles. The results from the pH-stat showed that 12.08 + 2.45 % of the FFA release occurred in the gastric phase. The remaining triglycerides lipolysis took place at the intestinal stage. The GC revealed that 97.69 % of these FFAs released at the gastric phase are MCFAs, namely, caprylic (50.01 %), capric (32.28 %), and lauric acids (15.39 %). Accordingly, results of GC from samples taken from the dynamic protocol displayed a similar FFA profile with caprylic acid (60.63 %) and capric (39.37 %) representing the major FFAs released in the stomach phase. However, it is worth to notice that although there is an agreement between the FFA profiles of samples from the static and dynamic protocols, the total concentrations of FFAs in samples taken from the static protocol (1796.60 mg/L) are higher than those obtained with the dynamic protocol (73.60 mg/L). These results suggest that GI systems control parameters such as continuous injection of secretions and stomach emptying procedures may influence the lipolytic potential of digestive lipases. Further studies need to be conducted to evaluate protocols performances with different oil samples.